They laugh at the fact that the Bible claims that people before the flood lived to be hundreds of years old. They also laugh at the idea that there was enough water to flood the whole earth and that it then receded somewhere.

I said these are kind of related, and I believe that they are. First let me quote from Genesis:

Genesis 1:6-7 And God said, "Let there be an expanse between the waters to separate water from water." [7] So God made the expanse and separated the water under the expanse from the water above it. And it was so.

So we see from this that God separated the water under the expanse (sky) from the water above the expanse (sky). Now think about what water above the sky would be like. Well it would most likely be very high in the atmosphere at the edge of space, which we know is very cold. So the water would have been an ice layer above the breathable atmosphere.

What would an ice layer like that do? It would filter out solar radiation for one. We know today that solar radiation has a lot to do with cancer and aging, both in animals and humans. So if this ice layer were to filter out some or all of this radiation, what would you expect to happen to those people and animals that lived under this filter? They would have less disease and live longer!

Secondly, an ice layer would cause a greenhouse effect on the earth, making the temperatures more moderate throughout the world. Could this explain the frozen animals in the Arctic that have been found with green vegetation in their stomachs?

Thirdly, it would put pressure on the atmosphere. What you would have is a natural barometric chamber covering the whole earth. Again, what would you expect that to do to the people and animals on the earth? All you have to do is look at what modern medicine and science use barometric chambers for today to find out the answer. If a person has a limb amputated and then reattached they are often placed in a barometric chamber and given high concentrations of oxygen to help the healing process. Now, remember the greenhouse effect the ice layer would have produced, meaning that there would have been more oxygen-producing plants on the earth. So the end result would be healthier and longer living humans.

1, Solar radiation includes light. It would have been darker, a lot darker. Darker than a very dark thing, at night, in a cave. We would have all suffered from vitamin D (?) deficiency.

2. By reducing the level of solar radiation striking the planet, it would have got colder, a lot colder. Colder than a cold thing, at night, in an ice cave. We would have all suffered from hypothermia and frostbite.

3. High concentrations of oxygen are toxic at increased pressure. We would have been going into convulsions.

In short, humans would have been cold, convulsing and suffering from rickets. We would't have lived longer but it may have felt that way.

An ice layer thick enough to block out all harmful solar radiation would...block out ALL solar radiation, harmful and otherwise.

For the record, visible light is solar radiation. So is heat.

It would also run the pressure up, true enough--at least if you suspend disbelief enough to believe that Earth was once encased in a thick, monolithic slab of ice somehow defying gravity by floating suspended at the top of the atmosphere without being vaporized by the sun in a matter of days. In fact, the pressure would be so great at ground level that the atmosphere would probably be turned into a high-pressure liquid.

Fourth, it would block out all sunlight. Causing all plant life to die instantly.
Only a few species of mould could survive in the dark world beneath the ice layer.
Of course the intense pressure generated by all that weight of ice resting ontop of the atmosphere, would generate a lot of heat.
So any life at all would be crushed and vaporized.
So much for your "ice layer"

"They laugh at the fact that the Bible claims that people before the flood lived to be hundreds of years old. They also laugh at the idea that there was enough water to flood the whole earth and that it then receded somewhere."

I certainly do.

"So the water would have been an ice layer above the breathable atmosphere."

Your "ice canopy" idea is severely flawed due to the fact that physics doesn't work that way, numbnuts.

"What would an ice layer like that do?"

Collapse. That's if it ever formed to begin with which, as I just pointed out, is physically impossible in the first place.

Assuming for a minute that it didn't collapse, it would reflect damn near all of the solar energy that hits the Earth which means that not only would you have an ice canopy, you'd have an ice planet as well.

"It would filter out solar radiation for one."

I fail to see why ice would filter solar radiation in any effective way.

"Secondly, an ice layer would cause a greenhouse effect on the earth, making the temperatures more moderate throughout the world."

We know today that solar radiation has a lot to do with cancer and aging

It has a lot to do with skin cancer, but little to do with anything else. You certainly can't live to 900 by avoiding the sun.

what would you expect to happen to those people and animals that lived under this filter? They would have less disease and live longer!

There's a lot more solar radiation at the equator than at the poles, so we'd also expect a correlation between lifespans and latitude. There's none that I'm aware of. Besides, the Bible says people continued to live to great ages for the next 400 years after the Flood.

Even Answers in Genesis admits that calculations by creationists themselves have proved the idea of an ice canopy is impossible and should be abandoned.

Horsefeathers: I fail to see why ice would filter solar radiation in any effective way.

Actually, if I remember my phd classes before I ran out of money it only takes less than an inch thickness of water to block 100% of the usable radiation that currently reaches the earth's surface. I suppose one could assume to have enough flood water, you could have an ice thickness great enough to block all solar radiation of the time... of course, then we are back to little to no vitamin D, photosynthesis, and basically what Rubber Chicken described. So, still fail.

1. Ice doesn't float in air.
2. Our atmosphere already blocks most harmful electromagnetic energy from the sun. We get radio waves, infrared or heat, visible light, and some ultraviolet. The atmosphere blocks UVC, some UVB, X-rays, and gamma rays. If you were to block out more of the spectrum, life probably wouldn't exist as we need visible light and infrared. (We also need radio, but not for existence.)
3. A greenhouse effect is not a good thing. You don't seem to understand what it means, so I'll explain it. Ultraviolet rays and visible light pass through the atmosphere and slow down, becoming visible light and infrared waves respectively. These lower energy waves hit the planet's surface and are reflected into the sky. The atmosphere blocks the infrared from escaping, reflecting it back toward the surface. This heats the planet to unlivable temperatures. Want proof? Venus has an atmosphere that traps heat through the greenhouse effect, and I believe its surface temperature is around 900 degrees Fahrenheit.
4. Higher pressure is not a good thing. Barometric chambers might help with some injuries, but that doesn't mean you would want to live in one, any more than you'd want to take penicillin every day of your life because it's used to cure infections.

The "expanse" is talking about the sky. The authors of Genesis thought there was a firmament or solid dome above the earth which contained the upper waters, which fell to earth as rain when floodgates in the firmament were opened. The sky existed below the firmament, through which the sun, moon, and stars moved. Above the firmament was heaven where God lived. They thought it looked something like this:

Hovind's "vapor canopy" idea is impossible, because it would block most if not all sunlight and either cause a nuclear winter or the atmospheric pressure would be too intense to survive.

Not to mention that the vapor canopy theory doesn't explain a bit where all that water which totally flooded the earth disappeared to.

That "ice layer" would fracture into thousands of icy asteroids, for the simple reason that a hollow, spherical shell cannot be stable at that size. If all these ice-asteroids fell to Earth at once, it wouldn't be a flood. It would turn the entire Earth to molten slag. In addition, these hypothetical ice-asteroids would gather in a belt orbiting the equator, providing no "protection" to people who live elsewhere, not to mention that mere water cannot stop high-energy radiation, so it would not even do anything to those at the equator. Ralph got his "argument" from Kent Hovind, and understands nothing about physics, chemistry, or biology.

Let's do some math. Deep sea exploration has confirmed that, by the time you go down 1000 m, all light from the sun is faded out. The Biblical account says that the ark eventually landed on Mt Ararat, which is some 5000+ m above sea level. That means you need 5000 m of water to cover that up (we'll even ignore the Himalayas which go up another 3800 m at the highest point). The proposed ice canopy would therefore have "filtered" so much solar radiation that the world would have been constantly bathed in darkness.

Would have been a nasty place for those oxygen-producing plants that Ralph mentions.